The intermittent feeders used in wire-processing machines draw off the wire from a wire coil placed on a pay-off reel, wherein they operate with high accelerations and brake applications. It is desired that the pay-off reel is to run as smoothly as possible, in order that the wire is continuously released. For this, deflecting means and/or swivel arms which are meant to compensate for irregularities in the drawing-off are usually used, as the very large mass of the wire coil for its part cannot be accelerated and decelerated very quickly.
However, the named remedial measures are often insufficient to ensure the desired smooth running of the pay-off reel or to achieve as little as possible to no movement of the swivel arm.
From DE 44 43 503 A1 an apparatus for feeding wire to wire-processing machines is known in which the wire coming from the pay-off reel is guided between the latter and the wire feeder of the downstream wire-processing machine in a loop, wherein the deflection of this loop is detected by a recognition unit. Besides the rotational movement for the unreeling, the pay-off reel can also perform a swivelling movement about the wire-feeding direction, the extent and direction of which is predetermined by the recognition unit. This makes it possible to compensate for the twisting of the wire, which is important in particular during the processing of hard-drawn wire types.
From JP 2004-122204 A a wire feeding is known in which a deflectable deflecting roller is used which is prestressed downwards in spring-loaded manner and functions similarly to a swivel an of a pay-off reel. The deflection of the deflecting roller is detected and the rotational speed of the pay-off reel is regulated accordingly.
In the wire-feeding apparatus, known from EP 0 255 507 B1, of the type named at the beginning, a spring-loaded, deflectable deflecting roller is likewise provided between a straightening rotor and a pay-off reel. In addition, after the straightening rotor, the wire is guided round in a freely running loop, the formation of which is monitored by means of switches. The spring-loaded, deflectable deflecting roller is associated with a sensing means which switches off the wire feeder and the straightening rotor when the length falls below a predetermined minimum value, while switches associated with the loop influence not only the conveying speed of the wire feeder, but also the rotational speed of the straightening rotor in the same direction.
Although these known apparatuses bring certain improvements with regard to a smoother running of the pay-off reels, it has been shown that the pay-off reel (and any swivel arm associated with it) still run far from smoothly in the case of intermittent draw-off movements.